Electric control switch with self locking contact



G. WINTRISS 3,189,720

ELECTRIC CONTROL SWITCH WITH SELF LOCKING CONTACT June 15, 1965 Filed March 2., 1962 no no IN V EN TOR.

BY M sum M c ATTORNEYS United States Patent 3,189,726 ELECTRIC CONTROL SWITCH WITH SELF LOCKING CONTACT George Wintriss, Carversville, Pa. Filed Mar. 2, 1962, Ser. No. 176,939 11 Claims. (Cl. 200-166) This application is a continuation-in-part of my copending application Serial No. 29,368, filed May 16, 1960, now Patent No. 3,078,515.

This invention relates to electric switch means for opening and closing a circuit, and the invention is more particularly concerned with switch means that are suitable for use in sensing apparatus for automatic machines where a circuit must be closed when parts reach certain positions and independently of lost-motion and manufacturing tolerances, in the switch means.

It is an object of the invention to provide an improved electric switch having one contact that is movable within a limited range and that has a controlled bias toward one end of its range of movement, and another contact movable toward and from the first contact and with a bias away from the first contact, and with both of the contacts permanently connected to different parts of an electric circuit. In the preferred construction the first contact is selflevelling; that is, it has restraining means that cause it to come back from a displaced condition very slowly so that with regular repetitive actuations, with each cycle of operation of a repeatedly running machine, the first contact will always be in an accurately determined position each time the switch means is operated and, therefore, will be operated at a definite time in the cycle of the machine.

It is another object of this invention to provide switch means that have a contact which is accurately positioned and which is part of an assembly contained in a shield that fits into a holder having a terminal in a circuit with the shield, and to provide an actuated contact movable to touch the accurately positioned contact and connected by a resilient support with a second terminal of the switch means.

The invention provides a unitary assembly which is compact and rugged and suitable for mounting on a machine as a detector of irregular operation of the machine, as disclosed in my co-pending patent application, Serial No. 29,368, filed May 16, 1960, now Patent No. 3,078,515.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views;

FIGURE 1 is a sectional View, on a magnified scale, of switch means made in accordance with this invention; and

FIGURE 2 is a sectional view taken on the line 2-2 of FIGURE 1.

The drawing shows a switch unit 42 which includes a housing 60 containing a chamber 62 in which there is a cylinder 64. The housing 60 is made of electrical insulating material and it has two terminals 66 and 68 extending from it.

The terminal 66 is electrically connected, by a coil spring conductor 70, with a contact consisting of a ball 72 at the upper end of a passage 74 which leads into the chamber 62. The upper end of this passage 74 permits the ball 72 to contact with the cylinder 64.

The chamber 62 is closed at one end by a flexible diaphragm 78 through which a button 80 extends. The button 80 is urged toward the left in FIGURE 1 by a spring 82, and this spring provides an electrical connection between the terminal 68 and the button 86. The top convolution of the spring 82 snaps into a groove 83 in the 3,189,?2ti Patented June 15, 1965 lower part of the button to connect the button and the spring.

When the button 80 is moved to the right, against the force of the spring 82, it contacts with one end of a piston rod 84' that extends through a diaphragm 36 and further movement of the button 80 displaces the piston rod 84- and moves a piston 88 toward the right against the pressure of a spring 99.

The apparatus is designed so that an actuator moves the button 80 into contact with the piston rod S4, and displaces this piston rod 84 and its piston 88. It should be noted that this movement is with a positive displacement and that the contact of the button 86 and piston rod 84 are made without transmitting motion through any resilient parts, as in the case of snap switches. Thus, the closing of the circuit between the terminals 66 and 68 corresponds to an exact position of the upper end of the piston rod 84.

In the construction shown in FIGURE 1, the piston rod 84 is of composite construction and includes a tubular portion 93 with a slit 94 through which the hollow and openended portion 93 communicates with the interior of the cylinder around the piston rod and beyond the piston 88.

The cylinder 64 is filled with liquid. The diaphragm 86 fits tightly around the piston rod 84 and extends into a circumferential groove 95 in the piston rod. The outer edge of the diaphragm 86 is sealed by a ring 96 which clamps the periphery of the diaphragm 86 against a packing ring 97 which is located above the peripheral edge of the diaphragm 86 and in a circumferential groove 93 formed in the wall of the cylinder 64.

Different kinds of liquid can be used in the cylinder 64 and the rate at which the piston 88 moves back to its orig inal position, under the influence of the spring 99, depends upon the viscosity of the liquid, since most of the liquid must pass through the slit 92 in going from one side of the piston to the other. If the liquid is not too viscous, some of it can pass through the running clearance between the piston 88 and the cylinder 64..

When the switch is used with automatic machines having a fixed cycle, the use of the proper liquid in the cylinder 64 can make the contact face on the end of the piston rod 84 a self-levelling contact. It is pushed down as much as necessary to permit an actuating bumper of the machine to complete its stroke, and by retarding the return of the piston rod, its contact face is in a desired posi tion for closing of the switch the next time the actuating bumper of the machine moves the button 80 into contact with the piston rod contact 84 on the next cycle.

A bushing 100 surrounds the upper part of the cylinder or shield 64 and fits over the shield 64 with a press fit. An outer shield portion 162 fits over the bushing 10% with a press fit. This outer shield portion 102 and the bushing 100 form the upper part of the housing 60 and are connected to the housing. A snap ring 104 fits into a circumferential groove 106 formed by a clearance between the upper end of the bushing 100 and a ridge 108 extending inwardly from the wall of the outer shield portion 102.

The lower convolution of the conical spring 32 fits into a circumferential groove 110 in the wall of the outer shield portion 162 just above the ridge 168. There is another circumferential groove 112 in the inside wall of the outer shield portion 102, and the periphery of the diaphragm 78 fits into this groove 112. It is not necessary to have any sealing ring or packing around the periphery of this diaphragm 78 because there is no liquid in the space between the outer diaphragm 78 and the inner diaphragm 86.

In the operation of the apparatus, a repetitively-moving part of a machine actuates the button 80 and moves it against the pressure of the spring 82 and into contact with t e piston rod contact S l. On the first actuation, this piston rod contact 84 is displaced toward the right in FIGURE 1, against the pressure of the spring 90.

This displacement of the piston rod contact 84 moves the piston rod 93 and the piston 88 so that liquid on the right of the piston 88 moves through the slot 94 into the space on the left-hand side of the piston 88.

As the machine continues its cycle and the button 80 is free to return to its original position under pressure from the spring 82, the viscosity of the liquid in the shield e2 prevents the spring 9% from moving the piston 88, the piston rod 93 and the piston rod contact as back to their original positions. While these parts will start back as soon as the displacing force has been removed, the viscosity of the liquid in the shield is such that the button 30 again moves into contact with the piston rod contact 84 before the latter has had time to travel for any consequential distance back from its displaced position. Thus the piston rod contact 84 is held back in a self-levelling position which automatically accommodates itself to the range of movement of the button 89 and the actuator which displaces the button 89.

It will be evident that the invention has the important advantage of obtaining accurate closing of the electric circuit at the end of the stroke of an actuator of the button 8!) regardless of the accuracy with which the switch assembly is mounted on a machine in which it is used. With regular operation of the machine, the piston rod contact 84 is always at an accurate position for closing the circuit when the actuated contact moves into switchclosing position with each cycle of operation of the machine.

While this use of the invention with repetitively-operating machines is the most important intended use of the invention, it will be apparent that it can be used for other purposes where a compact switch assembly of this character is useful.

The preferred embodiment of this invention has been illustrated and described but changes and modifications can be made and some features can be used in diflerent combinations without departing from the invention as defined in the claims.

What is claimed is:

1. An electric switch including a first contact, a support for the first contact including a piston, a cylinder within which the piston slides with reciprocating movement within a limited range, end walls closing both ends of the cylinder and forming chambers on both sides of the piston for a confined fluid, means urging the piston support toward one end of its range of travel, a second contact movable toward and from the first contact and into position to displace the first Contact against the pressure of the means urging the movable support toward one end of its range of travel, other means urging the second contact away from the first contact, a conductor permanently connected in the electric circuit with the first contact, and another conductor permanently connected in the electric circuit with the second contact.

2. The electric switch described in claim 1 and in which there is a piston rod extending from one end of the cylinder, and the second contact is on the extending end of the piston rod.

3. The electric switch described in claim 2 and in which there is a flexible diaphragm surrounding the piston rod and connected around its periphery with the cylinder for closing the end of the cylinder from which the piston rod extends.

4. An electric switch including a first contact, a support for the first contact movable within a limited range, a guide on which the support moves, means urging the movable support toward one end of its range of travel, a second contact movable toward and from the first contact and into position to displace the first contact against the pressure of the means urging the movable support toward one end of its range of travel, other means urging the second contact away from the first contact, a conductor permanently connected in the electric circuit with the first contact, and another conductor permanently connected in the electric circuit with the second contact, a cylinder, the movable support for the first contact being a piston that reciprocates within the cylinder, and the means urging the .movable support toward one end of its range of travel being a spring in the cylinder behind the piston, a piston rod extending from one end of the cylinder, the second contact being on the extending end of the piston rod, a flexible diaphragm surrounding the piston rod and connected around its periphery with the cylinder for closing the end of the cylinder from which the piston rod extends, the cylinder having liquid therein and there being an opening in the piston through which liquid travels from one side of the piston to the other when the piston is displaced lengthwise of the cylinder whereby the cylinder and piston operate as a dash pot to limit'the rate of return of the first contact toward the second contact after the first contact has been displaced by said second contact.

5. An electric switch including a first contact, a support for the first contact movable within a limited range, a guide on which the support moves, means urging the movable support toward one end of its range of travel, a second contact movable toward and from the first contact and into position to displace the first contact against the pressure of the means urging the movable support toward one end of its range of travel, other means urging the second contact away from the first contact, a con-- ductor permanently connected in the electric circuit with the first contact, and another conductor permanently connected in the electric circuit with the second contact, a diaphragm surrounding the second contact, the periphery of the diaphragm being connected with a fixed support whereby the diaphragm limits movement of the second contact away from the first contact, the means of urging the second contact away from the first contact being a spring.

6. The electric switch described in claim 5 and in which the fixed support is a cylinder in which both the first contact and its piston are contained.

7. The electric switch described in claim 6 and in which the movable support for the first contact is a piston, and there is an inner cylinder in which the piston slides, and the inner cylinder fits within the cylinder that is the fixed support for the diaphragm that surrounds the second contact, and the inner cylinder is shorter than the outer cylinder into which it fits so that the first contact is also contained within said other cylinder.

8. The electric switch described in claim 7 and in which the inner cylinder is made of electrical conductive material and the other cylinder is made of material that is an electrical insulator, and there is a brush on the inside of said other cylinder in position to Contact with the inner cylinder, and the means urging the second contact away from the first contact is a metal spring, and there is a terminal connection on said other cylinder in contact with the metal spring.

9. An electric switch. including a first contact, a support for the first contact movable within a limited range, a guide on which the support moves, means urging the movable support toward one end of its range of travel, a second contact movable toward and from the first contact and into position to displace the first contact against the pressure of the means urging the movable support toward one end of its range of travel, other means urging the second contact away from the first contact, a conductor permanently connected in the electric circuit with the first contact, and another conductor permanently connected in the electric circuit with the second contact, an actuator movable through a stroke and into and out of contact with the second contact, the stroke of the actuator being long enough to move the second contact to the first contact and to then displace both contacts for a limited distance, the actuator itself being a contact in an electric circuit and connecting said second and first contacts in said electric circuit when the second contact is displaced far enough to touch the first contact, and separate conductors leading from each of the first and second contacts.

19. The electric switch described in claim 9 and in which there is a cylinder, and the movable support of the first contact is a piston movable within the cylinder, and the means urging the movable support toward one end of its range of travel is a spring in the cylinder behind the piston, and there is a piston rod extending from one end of the cylinder with the second contact on the 6 surrounding the piston rod and connected around its periphery with the cylinder for closing the end of the cylinder from which the piston rod extends.

11. The electric switch described in claim 10 and in which there is a second spring urging the second contact away from the first contact and this second spring is a part of the electric circuit of the second contact.

References Cited by the Examiner UNITED STATES PATENTS 2,039,838 5/36 Saudicoeur 200-l48 BERNARD A. GILHEANY, Primary Examiner.

extending end of the piston rod, and a flexible diaphragm 1 ROBERT K. SCHAEFER, Examiner.

UNITED STATES PATENT OFFIQE CERTIFICATE OF CORRECTION Patent No. 3,189,720 June 15, 1965 George Wintriss It is hereby certified that error appears in the above numbered patent reqliring correction and that the said Letters Patent should read as correctedbelow.

Column 3, lines 50 and 51, strike out "support".

Signed and sealed this 30th day of November 1965.

(SEAL) Altest:

ERNEST W. SWIDER Commissioner of Patents 

1. AN ELECTRIC SWITCH INCLUDING A FIRST CONTACT, A SUPPORT FOR THE FIRST CONTACT INCLUDING A PISTON, A CYLINDER WITHIN WHICH THE PISTON SLIDES WITH RECIPROCATING MOVEMENT WITHIN A LIMITED RANGE, END WALLS CLOSING BOTH ENDS OF THE CYLINDER AND FORMING CHAMBERS ON BOTH SIDES OF THE PISTON FOR A CONFINED FLUID, MEANS URGING THE PISTON SUPPORT TOWARD ONE END OF ITS RANGE OF TRAVEL, A SECOND CONTACT MOVABLE TOWARD AND FROM THE FIRST CONTACT AND INTO POSITION TO DISPLACE THE FIRST CONTACT AGAINST THE PRESSURE OF THE MEANS URGING THE MOVABLE SUPPORT TOWARD ONE END OF ITS RANGE OF TRAVEL, OTHER MEANS URGING THE SECOND CONTACT AWAY FROM THE FIRST CONTACT, A CONDUCTOR PERMANENTLY CONNECTED IN THE ELECTRIC CIRCUIT WITH THE FIRST 